JPS60120728A - Painting or printing method - Google Patents

Abstract

PURPOSE:To facilitate formation of a stiff coating film on a nonpolar plastic, by priming the plastic with each of alpha-cyanoacrylate and aluminum alcoholate before painting or printing. CONSTITUTION:A solution of about 0.001-10wt% aluminum alcoholate or aluminum chelate compound (e.g., aluminum isopropylate) in an organic solvent (e.g., toluene or butyl acetate) is applied to a base of a nonpolar plastic (e.g., polyolefin) and dried to form a film, which may be monomolecular. An alpha-cyanoacrylate (e.g., isopropyl alpha-cyanoacrylate) is applied onto this film to form a coating film of a thickness of about 10-50mu. The primed base is painted with an ordinary paint or printed with a printing ink.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coating or printing method, which is suitable for coating or printing on materials conventionally considered difficult to coat or print on, such as non-polar or highly crystallized glass substrates. It relates to a method of applying painting or printing.

In particular, the present invention applies coating to the surface of non-N materials made from polyolefins such as polyethylene, polyglopylene, and co-minimal combinations thereof, which are non-polar, highly crystallized plastics that have been particularly difficult to paint or print. Or, it relates to an excellent coating or printing method that makes it possible to print well.

Since polyolefin is a non-polar and crystalline glass material, it has the drawback of poor adhesion to paints or printing inks and the inability to form a practical coating film using conventional methods, making it an unsuitable material for painting or printing. In order to paint or print on these materials, the surface of the polyolefin must be subjected to flame treatment, corona discharge treatment, ozone treatment,
One method has been proposed in which the surface is oxidized by plasma jet treatment or dichromate or sulfate treatment to generate polar groups such as carbonyl groups, and then painting or printing is performed.

However, these methods have problems in the process, such as not being able to uniformly treat objects with complex shapes, requiring special processing equipment, and making the work complicated.

As an improvement to these methods, 4-\UFj
2-98062, 56-141328 and 57-
No. 119,929 proposes a one-piece coating composition prepared by dissolving chlorinated polyethylene, chlorinated carbon, or fatty acid-modified acrylated alkyd resin in an organic solvent.

However, according to JP-A-58-8734, these coating agents have good adhesion to polyolefins, but 1B) have poor adhesion to topcoat paints, or have poor adhesion to topcoat paints and polyolefins. It has been pointed out that even if the film shows good adhesion, the inter-film adhesion V1mi decreases due to repeated cooling and heating cycles.

Also, JP-A No. 54-124048, No. 124049, No. 1
According to 24095, solid rubber on a polyolefin base material,
They have proposed modified polyolefins containing unsaturated carboxylic acids or derivatives thereof and radical generators, but according to JP-A-57-38827, these methods leave unreacted unsaturated carboxylic acids, radical generators, etc. It is said that this has an undesirable effect on the adhesion of the paint film.

Furthermore, JP-A-54-12405+], JP-A-55-3427
0, No. 55-84274, an improved resin containing a propylene/styrene/butadiene block copolymer and an inorganic filler as essential components is proposed, but this method also suffers from poor weather resistance and poor weather resistance in non-coated areas. It seems that there are problems such as low-temperature brittleness caused by filler formulation.Painting or printing on the surface of a polyolefin base material is considered to be polyolefin, and If an excellent coating or printing method is developed, it is thought that it will make a significant contribution to various fields such as the automobile industry and electrical equipment.

In view of this situation, as a result of intensive research efforts, the unexploited town names developed a painting or printing technique that achieves the intended purpose, and have now completed the present invention.

That is, the present invention uses α as a coating agent for painting or printing.
- characterized by using cyanoacrylate and aluminum alcoholade or aluminum chelate compound 1
- Concerning filter coating or printing methods.

The α-cyanoacrylate used in the method of the present invention is represented by the following general formula.

N/CII, =C\OOR In the above formula, R includes alkyl, alkenyl, cyclohexyl, Cryl, alkoxyalkyl, etc., and specifically, methyl, ethyl, n-propyl,
Examples include n-butyl, isobutyl, n-pendel, allyl, cyclohexyl, hensyl, and methoxyfurovir groups.

These α-cyanoacrylates are commercially available silica
It is a main component of noacrylate instant adhesives, and in the present invention, commercially available adhesives such as these can be used as they are. In particular, in the present invention, commercially available low viscosity grades are suitable for use as primers for painting or printing.

Further, in the present invention, α-cyanoacrylate can also be used after being diluted with a specific organic solvent.

Suitable organic solvents include toluene, butyl acetate, or methyl chloroform, which are compatible with α-cyanoacrylate and do not impair stability, and these solvents do not contain water or other impurities. is preferred.

Further, the aluminum alcoholade or aluminum chelate compound used in the method of the present invention has both a polar segment and a non-polar segment in its molecule and has unique reactivity. There are the following:

Aluminum isopropylate Aluminum mono-5ee-butoxydiingropylate Aluminum trisacetylacetonate Aluminum monoacetylacetonate Bisethyl acetoacetate Aluminum ethyl acetoacetate Diing globilate Aluminum tris ethyl acetoacetate Aluminum oleyl acetoacetate Diisoglobilate Above Although it is also possible to use the aluminum alcoholade or aluminum chelate compound by dissolving it in α-cyanoacrylate as described below, it is preferable to use it by dissolving it in an organic solvent separately from (X-cyanoacrylate.Organic solvent The above aluminum alcoholade or aluminum chelate compound can be completely dissolved or dispersed, and has appropriate volatility;
It is also desirable that it be easily available industrially.

Furthermore, it is preferable that the solvent be able to completely wet the surface of the base material such as polyolefin, and for this purpose, it is best to select and use an organic solvent whose surface tension is smaller than the critical surface tension γC of the base material. It is desirable. The following table shows typical values of surface tension.

In the method of the present invention, α-cyanoacrylate and an aluminum alcoholade or an aluminum chelate compound are used as an undercoat for painting or printing at a temperature of 0.degree.

A simple method is to apply a mixture of α-cyanoacrylate and aluminum alcoholade or an aluminum chelate compound, and if necessary, a solution diluted with an organic solvent to the surface of the substrate to be painted or printed, or 2. It is also possible to adopt a method of simultaneously discharging a solution of α-cyanoacrylate and an aluminum alcoholide or an aluminum chelate compound using a liquid discharging type coating machine. However, when adopting the mixed method, II
- Since cyanoacrylate exhibits strong anionic activity and has unique properties, sufficient care must be taken when handling to avoid contamination with foreign substances such as moisture, amines, and gamma alcohol.

In the method 1.1 of the present invention, simple methods such as those described in 1.1 can also be adopted, but in order to fully exhibit the intended effects of the present invention, the following steps must be taken. It is preferable to apply it by the method 12.

First, as a first step, the surface of the substrate to be painted or printed is coated with aluminum Alcorado or +:L '7"
A solution of a luminium chelate compound dissolved in an organic solvent is applied.

At this time, the concentration of σ)m class 0) is preferably 0001 to 10% by weight. The aluminum alcoholade or aluminum chelate compound applied to the surface of the base material can sufficiently exhibit the desired effect of the present invention if it is in the form of a monomolecular film, and if the concentration is 0001%. It becomes easier to achieve that purpose, and as the concentration (C) increases, the film of the aluminum alcolade or aluminum chelate compound becomes thicker in proportion to it, and if it becomes too thick, the layer becomes a brittle layer. be.

The method for applying the above solution to the surface of the base material is the usual brushing method,
It can be done by dipping or spraying method, etc., and the open time after treatment is usually 5 to 6 minutes at room temperature.
It takes 0 minutes, but it can take several days depending on the work process.

As a second step, apply α-cyanoacrylate onto the treated substrate to form a film of α-/anoacrylate polymer.

The α-cyanoacrylate can be applied by a brushing method using a brush treated with an acid in advance, a dipping method, a spraying method, or the like.

However, when using the spray method, it is preferable to use a diluted solution of α-cyanoacrylate in an organic solvent to prevent problems with nozzle clogging.

The substrate coated with α-cyanoacrylate is 12
It is left for more than 1 hour to form a thin layer of α-cyanoacrylate polymer on its surface.

The film thickness of the α-cyanoacrylate polymer is not particularly limited (but it should be 10 to 50 t to avoid glue-free areas).
It is preferable to set it to about t.

By the following method, the substrate coated with the primer is painted with a general paint or printed with printing ink.

There are various types of paints or printing inks, and there are various classification methods, but the following methods can be used for vehicle resin acid fractionation.

Rosin derivatives, nitrocellulose resins, vinyl resins, acrylic resins, polyester resins, polyamide resins, polyurethane resins, phenolic resins, epoxy resins, aminoalkyd resins, melamine resins,
Any UV-curable acrylic oligomer can be used in the present invention, but depending on the intended use, paints based on polyurethane resins, epoxy resins, alkyd resins, etc. are more suitable for use in polyolefins. Particular preference is given to printing inks.

Furthermore, since there is a limit to the heat resistance of the base material of the baking paint, especially the plastic, especially the polyolefin, it is preferable that the baking temperature is 90° C. or lower.

The coating method can be done by conventional methods such as brushing, bar coater, roller or spraying, while the printing method can be done by conventional methods such as silk screen printing, gravure printing or flexographic printing. It can be done by method.

The reason why the paint or printing ink adheres firmly to the surface of the substrate, especially polyolefin, by the method of the present invention is not clear, but it is presumed to be based on the following principle.

In other words, when an aluminum alcoholade or aluminum chelate compound is applied to the surface of a polyolefin base material, it partially penetrates into the interior, and polar molecules show affinity with polar molecules, and non-polar molecules show affinity with non-polar molecules.
Based on the theory of 5 stability parameters, the nonpolar segment of the aluminum alcoholade or aluminum chelate compound and the polyolefin are strongly bonded as a secondary bond, and the polar molecules of aluminum oxide are oriented on the surface of the polyolefin. Next, α on this surface
- When cyanoacrylate monomer is applied, due to its electronic properties, α-cyanoacrylate and aluminum oxide are strongly bonded primarily or secondarily, forming a film of α-cyanoacrylate polymer having polar groups on its surface. Ru.

This is probably because when a paint or printing ink is subsequently applied to this surface, a strong coating film is completed due to secondary bonding, which resists the attraction of each polar molecule.

The process of the present invention is particularly useful for polyolefins, but also for other non-polar or highly crystallized plastics such as polyethylene terephthalate, polyacetals, nylons, etc. Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Example 1, Comparative Examples 1 to 3 The following were used as the undercoat and paint.

Undercoat 1 A solution in which 0.2 gr of aluminum isopropylene was uniformly dissolved in 99.8 gr of toluene Undercoat 2 Ethyl α-cyanoacrylate 988a (stabilizer, sulfur dioxide gas 50 ppm) / Hydroquinone 100 ppm
Contains, manufactured by Toagosei Chemical Co., Ltd.) Paint (1) Nitrocellulose lacquer enamel (blue) spray type (Nippon Paint) (2) Nitrocellulose lacquer enamel (white) spray type (
(manufactured by Kansai Paint) (3) Nitrocellulose lacquer enamel (yellow) spray type (manufactured by Kansai Paint) A polyethylene plate 100100X100X2 Hi-Zex 5000H (manufactured by Mitsui Petrochemical Industries) was used as the base material, and primer 1 was applied to the surface. It was brushed and allowed to air dry at room temperature for 10 minutes. Next, this base-treated polyethylene board was immersed in Primer 2 and immediately taken out and left at room temperature for 24 hours.

The paint was evenly sprayed onto the surface of the polyethylene plate coated with the primer in this way and left at room temperature for 7 days.

The adhesion of the coating film was measured by a goblin test in accordance with JIS D0202.

Comparative example 1 The procedure was the same as in Example 1 except that the undercoating was omitted.

Comparative example 2 The procedure was the same as in Example 1 except that the undercoat 1 was omitted.

Comparative example 6 Undercoat 2 was omitted (other than that the same as Example 1).

The results are shown in Table 1.

Example 2 The following were used as the undercoat and paint.

Primer 1 Aluminum-mono-acetylacetonate bis-ethylacetoacetate aluminum-ethylacetoacetate diisopropylate aluminum tris-ethylacetoacetate aluminum-oleylacetoacetate diisopropylate 0.5 gr of each of these compounds in methyl chloroform 99 A solution uniformly dissolved in .7 gr.

Undercoat 2 Inpropyl α-cyanoacrylate 0 @ 49 (stabilizer, sulfite residue 50 ppm) Idoquinone 100
Acrylic resin paint (yellow) (manufactured by Toagosei Kagaku Kogyo) (contains ppm) Acrylic resin paint (yellow) (manufactured by Toagosei Kagaku Kogyo) The base material is a polypropylene plate 100 x 100 x 2 mm (K
SM, Mitsui Noblen), and apply primer 1 on the surface.
was applied with a brush and allowed to air dry for 5 minutes.

Next, this polypropylene plate was immersed in Primer 2 and immediately taken out and left at room temperature for 24 hours.

Subsequently, a paint was brushed onto the surface of this polypropylene plate and left at room temperature for 7 days.

The results are shown in Table 2.

Example The following were used as the undercoat and paint.

Undercoat 1 A solution in which 0.5 gr of aluminum mono-5ec butoxodiisogropyrate was uniformly dissolved in ethyl acetate A/99.5 gr.

Undercoat 2 Isobutyl α-cyanoacrylate 0.e.(Note) 50
gr is ethyl acetate reagent grade 1 (manufactured by Katayama Chemical) 50 g
It was prepared by uniformly mixing it with r.

(Note) (Contains stabilizer, 100 ppm of sulfur dioxide gas, 200 ppm of hydroquinone, manufactured by Toagosei Chemical Co., Ltd.) Paint: 2-component polyurethane paint (brown) (manufactured by Chugoku Paint Co., Ltd.) Base material: polypropylene board 100 x 100 x 2 Fight (K
Undercoat 1 was brushed onto the surface using Mitsui Noblen (SM Mitsui Noblen) and air-dried for 5 minutes.

Next, the undercoat 2 was uniformly sprayed onto the surface of this polypropylene plate using a spray gun and left at room temperature for 24 hours.

Subsequently, a paint was uniformly sprayed onto the surface of this polypropylene plate using a spray gun and left at room temperature for 7 days.

The performance of the paint film was evaluated by a cross-cut test at room temperature and by observing the presence or absence of cracks and peeling of the paint film after the next environmental exposure test.

The cycle of environmental exposure conditions + 11 UV/wet cycle UV - 60°C/4 hours -> water vapor - 40°C/4 hours was repeated 25 times.

Apparatus: UVCON tester (manufactured by Toyo Seiki ■) (2) Heat resistance Heated in hot air at 80°C for 24 hours.

Equipment: Lab oven (manufactured by Tabai Seisakusho) (3) Water resistance It was immersed in tap water at room temperature for 24 hours.

(4) A cycle of thermal shock of 0° C./1 hr−+ 60° C./1 hr− was repeated 30 times.

Apparatus: Model TSC-10A (manufactured by Tabai Seisakusho) The results are shown in Table 6.

Claims (1)

[Claims] 1. A painting or printing method characterized by using α-cyanoacrylate and aluminum alcoholade or an aluminum chelate compound as an undercoat for painting or printing.